1. Field of the Invention
This invention relates to shipping and storage containers, particularly of a tray shape, with moveable partitions which are pressed into place to allow the tray to be configured for different sizes or quantities of material.
In particular, this invention solves the problems that arose from the need to ship lead frames for integrated circuit manufacturing. As shown in FIG. 1, lead frames are thin metal strips with complex holes and trimmed areas. The strips are generally 0.01 inches thick and from 0.50 to 2.50 inches high, and vary in length from 6 to 10 inches. After plating with gold or silver, the strips are stacked together in a bundle for shipping. For example, 100 strips stacked and wrapped together would form a bundle nominally one inch thick. Because the strips are formed of metal, a bundle of them has substantial weight, and this weight requires special consideration in packing and shipping. Because of the plating, movement within the bundle must be prevented to eliminate scratching of the plated surfaces, and because the ends of the cut strips are delicate, shifting of the bundles within a container during shipment can cause the strips to be bent or deformed.
Therefore, a shipping container was required that could separate and support the bundles, accommodate various sizes and lengths of bundles, and provide sufficient cushioning to prevent damage to the bundled strips.
2. Description of the Prior Art
Shipping of bundles of lead frames was previously done in cardboard boxes. However, damage often occurred to the corners and ends of the bundle, and to the strips on the front and back face of the bundle. Damage occurred even though additional cushioning material was included in the box, because the bundles were packed adjacent to each other. Also, a multitude of box sizes were required for the many sizes and lengths of strips and bundles. Further, the cardboard boxes were often packed together into a larger box, which quickly became excessively heavy, and the weight of the boses in the top rows damaged the bundles in the bottom rows.
A possible improvement was the divided bin shown in FIG. 2. This bin can hold several bundles and separate the bundles with the flat vertical dividers. However, the limited number of divider positions means the bundles can still rattle around between the dividers, and no adjustment is provided to accommodate the many different lengths of bundles. These bins have been seen only in hard, rigid material which could not provide sufficient shock absorbing and cushioning. Because they are usually reused inside a factory, they have not been made inexpensive enough for discarding after one use, which would be required for use as a shipping container.
Another possible shipping method is illustrated in FIG. 3. This method uses inserts and spacers of cushioning material between the bundles and the box. While this would provide for close contact to support and cushion the bundles, it is not adaptable to multiple sizes of bundles without a multitude of sizes and inserts and boxes.
FIG. 4 shows another possible shipping method. This tray is molded of expanded polystyrene or other stiff but compressible foam or plastic. The formed holes properly support and separate the bundles. The problem with this design is that for every different size of bundle, a different tray is required. Since molds are required for each size, there is considerable expense and manufacturing lead time in preparing molds, and in building an inventory of trays in various sizes. Considerable storage space is also required for many different size trays.